Disable the Windows 8.6.4 test

Author: pepeiborra

.github/workflows/test.yml

@@ -20,6 +20,8 @@ jobs:
           - os: windows-latest
             ghc: "8.8.2" # fails due to error with Cabal
         include:
+          - os: windows-latest
+            ghc: "8.6.4" # times out after 300m
           - os: windows-latest
             ghc: "8.10.2.2" # only available for windows and choco
           # one ghc-lib build